The present invention pertains to a process and apparatus for precisely transferring solutions at high speed. More particularly, it pertains to such a process and apparatus especially useful for the compounding of hyperalimentation solutions.
Hyperalimentation therapy is the intravenous feeding of, for example, a protein-carbohydrate mixture to a patient. It is used primarily to meet the patient's protein and caloric requirements which are unable to be satisfied by oral feeding. The protein may be in the form of free-amino acids or protein hydrolysate and the carbohydrate commonly is dextrose. In addition to the protein and carbohydrate, vitamins (water-soluble and fat-soluble) and electrolytes also can be supplied in this therapy.
Each of these parenteral ingredients and the combination thereof are particularly susceptible to the growth of deleterious organisms and it is desirable that they be administered to the patient in a sterile condition. Thus, because these protein and carbohydrate solutions cannot be pre-compounded by the manufacturer, but must be combined at the time of their use, their compounding must be performed under sterile conditions to avoid organism growth.
A known apparatus and process for compounding hyperalimentation solutions utilizes a solution transfer system including a receiving container and a Y-transfer set. The Y-transfer set includes two separate tubes, each having an end attached to a common juncture by which solutions delivered through the tubes will pass through the juncture into the receiving container. The other end of one tube of the set is attached to the protein holding container and of the other tube of the set to the carbohydrate holding container. The desired volume of each solution being transferred to the container is controlled by a clamp placed on each tube. The solutions may be allowed to flow into the receiving container by gravity flow. However, it has been found to be useful to transfer the solutions under the influence of a vacuum applied to the receiving container. When the receiving container is a flexible plastic container, the vacuum is created in a vacuum chamber into which the container is placed.
It has been known in the past that to ensure sterility during the compounding of hyperalimentation solutions, compounding should be performed under a laminar flow hood. Laminar flow hoods are used for reducing the risk of airborne contamination of such solutions. These units operate by taking room air and passing it through a pre-filter to remove gross contaminates, such as dust and lint. The air is then compressed and channeled through a bacterial retentive filter in the hood in a laminar flow fashion. The purified air flows out over the entire work surface of the hood in parallel lines at a uniform velocity. The bacterial retentive type of filter is designed to remove all bacteria from the air being filtered.
Compounding under a laminar flow hood aids in preventing airborne contamination, but it is relatively cumbersome and expensive and would not be useful for eliminating any other source of contamination, such as contamination caused by handling. When using a hood the operator may inadvertently perform the work at the end or outside of the hood and not within the recommended space, at least six (6) inches within the hood, which insures the benefits of the air being purified. Time must be taken and care must be exercised to maintain a direct open path between the filter and the compounding area. Solution bottles and other nonsterile objects cannot be placed at the back of the hood work area next to the filter because these objects could contaminate everything downstream and disrupt the laminar flow pattern of the purified air. Also, in using a laminar flow hood, it is necessary routinely to clean the work surface of the hood before any compounding is performed.
Thus, the prior art apparatus and process discussed above are disadvantageous due to the extensive number of hand operations which are time consuming and can be error prone.
An apparatus and process utilizing a filter system in the compounding operation poses new problems. The viscosities of some of these parenteral solutions could cause filter clogging and, consequently, retard transfer through the filter and apparatus. Also, the viscosities of the solutions may be and are generally different, which could lead to an unequal or otherwise undesired mixture of them. Therefore, additional time and care must be exercised to ensure that the desired mixture of the solutions being combined is achieved.
The process and apparatus of the present invention overcomes the above-discussed disadvantages. Further, the present invention provides quick and accurate delivery of fluids for compounding, especially sterile fluids. The present invention also provides automatic control for the delivery of fluids as well as sensing the amount of fluid in a collection container.